Hello , i have same problem but MBs arent 5 maybe 100-300 mb and after that wi-fi block!
i think the prolbem is from Intel(R) PRO/Wireless 3945ABG Network Adapter
When i try to watching some Flash (longer 3 min+) Wi-Fi Connection - blocked!!
If I try to download something from torrent client - same
I tryed with Netgear/D-Link/Edimax Routers - same
I tryed 2 Wi-Fi Drivers release + 1 from windows - same
If Some got any ideas thx for help.